The field of the invention is that of metal foil materials and the invention relates more particularly to foils of high strength titanium alloys and titanium aluminides and the like and to methods for manufacturing foils of such materials.
Composite materials of titanium aluminides reinforced with silicon carbide fibers have been proposed for use in aerospace applications. Such composite materials display high strength at elevated temperatures. Other high strength titanium alloys are also proposed for use in metal matrix composites and in honeycombs and the like. If titanium aluminide or titanium alloy foils could be manufactured at reasonable cost with consistently high strength characteristics, they would find wide application in fabricating metal matrix composites and honeycombs.
However, due to their ordered crystal structures, titanium aluminides based on the Ti.sub.3 Al (alpha two) and TiAl (gamma) intermetallic compounds possess limited cold and hot workability. Other high strength titanium alloys also have limited ductility. Accordingly it has been difficult to produce foils of such materials from ingot form by a succession of conventional rolling and annealing steps or the like, and low process yields using such procedures substantially increase the cost of such foils. Further, such materials usually have required cross-rolling to avoid development of undesirable textures in the materials so that it has frequently not been possible to obtain substantial lengths of coiled foil materials for use in fabricating composites or honeycombs or the like in an inexpensive manner. Recently it has been proposed that titanium alloy or titanium aluminide foils be formed by plasma deposition of such materials on a receiving surface as shown in U.S. Pat. No. 4,775,547, U.S. Pat. No. 4,782,884, U.S. Pat. No. 4,786,566, U.S. Pat. No. 4,805,294, U.S. Pat. No. 4,805,833 and U.S. Pat. No. 4,978,585. After peeling such deposited materials from the receiving surface, the peeled strip has been passed between pressure rolls to be consolidated and reduced to a desired foil thickness. However those known plasma-deposited materials are found to display less than satisfactory density as deposited and tend to be subjected to cracking and the like as they are consolidated by pressure rolling so that they tend to display less than fully desired density and strength when placed in actual use.
It would be desirable if titanium aluminide and high strength titanium alloy foils and the like could be produced in coiled, continuous strip form for use either in monolithic form or in titanium-based composite materials and honeycombs and the like while also being adapted to display desirable high strength, high density and freedom from cracking.